A common way to form images on media, such as paper, is to use a fluid-ejection device, such as an inkjet-printing device. An inkjet-printing device has a number of inkjet nozzles that eject ink, such as differently colored ink, in such a way as to form a desired image on the media. Many inks are dye-based, whereas other inks are pigment-based. In some formulations, these inks may be or may become relatively viscous.
Such viscous inks can form viscous sludge inside the inkjet nozzles. This sludge can affect typical testing, such as single drop detect testing, to determine whether the inkjet nozzles properly eject the ink. For instance, the performance of a single drop detect test may result in an inkjet nozzle using a pigment-based ink being seemingly OK to properly eject ink, only to fail to eject ink thereafter.
When an inkjet nozzle has failed a test to determine whether it is properly ejecting ink, generally the nozzles undergo servicing so that they can indeed properly eject ink. Typically, the nozzles undergo servicing such that a least-severe servicing event is performed first. The least-severe servicing event causes less ink to be ejected than more-severe servicing events. However, this conventional approach of servicing can greatly lengthen the time it takes to service an inkjet nozzle for pigment-based inks.
So-called “spitting,” or ejecting, of ink from an inkjet nozzle has been found to be an efficient way to remove large volumes of ink from an inkjet mechanism, such as an inkjet printhead, including the nozzle, when needed. However, in the case of pigment-based inks, such spitting can result in viscous sludge forming on the inkjet mechanism. This conventional ink spitting is thus disadvantageous as well.